Oestriol MCQs With Answer

Oestriol MCQs With Answer

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Oestriol MCQs With Answer provides B. Pharm students a focused, clinically relevant review of oestriol — an estrogen predominantly elevated in pregnancy. This concise set explores oestriol’s biosynthesis from fetal and placental precursors, pharmacokinetics, metabolism (sulfation/glucuronidation), receptor affinity, clinical assays (uE3, serum), diagnostic roles in fetal health screening, therapeutic uses in menopausal vaginal atrophy, formulations, dosing considerations, adverse effects, and drug interactions. Emphasis is placed on differences from estradiol/estrone, laboratory interpretation, and pharmaceutical aspects like stability and compounding. These MCQs reinforce deep understanding for practice and exams. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary source of maternal oestriol during pregnancy?

  • Maternal ovarian granulosa cells
  • Placental synthesis directly from cholesterol
  • Fetal adrenal DHEA-S converted by fetal liver and placenta
  • Maternal adipose tissue aromatization

Correct Answer: Fetal adrenal DHEA-S converted by fetal liver and placenta

Q2. Which statement best describes oestriol’s estrogenic potency compared to other endogenous estrogens?

  • Oestriol has greater uterotrophic potency than estradiol
  • Oestriol is equipotent with estradiol at estrogen receptors
  • Oestriol is a weak estrogen with lower receptor affinity than estradiol
  • Oestriol is inactive and acts only as an estrogen precursor

Correct Answer: Oestriol is a weak estrogen with lower receptor affinity than estradiol

Q3. In prenatal screening, a low maternal unconjugated oestriol (uE3) level most commonly suggests which condition?

  • Maternal hypothyroidism
  • Fetal adrenal hypoplasia or aneuploidies like trisomy 21
  • Maternal polycystic ovarian syndrome
  • Placental abruption

Correct Answer: Fetal adrenal hypoplasia or aneuploidies like trisomy 21

Q4. Which analytical method offers the highest specificity for measuring serum oestriol in modern laboratories?

  • Conventional ELISA without extraction
  • Radioimmunoassay (RIA) with crude serum
  • Gas chromatography-mass spectrometry (GC-MS) or LC-MS/MS after derivatization/extraction
  • Colorimetric steroid assay

Correct Answer: Gas chromatography-mass spectrometry (GC-MS) or LC-MS/MS after derivatization/extraction

Q5. Which metabolic reaction is most important for oestriol elimination?

  • Sulfonation and glucuronidation followed by urinary excretion
  • CYP-mediated hydroxylation to estradiol
  • Direct renal excretion of free oestriol only
  • Reductive deconjugation in plasma

Correct Answer: Sulfonation and glucuronidation followed by urinary excretion

Q6. The rise in maternal oestriol during pregnancy primarily reflects which physiological process?

  • Increased maternal ovarian follicular activity
  • Enhanced placental aromatization of maternal and fetal androgens, driven by fetal adrenal DHEA-S
  • Maternal hepatic overproduction of sex hormone-binding globulin
  • Increased conversion of estradiol to oestriol in maternal adipose tissue

Correct Answer: Enhanced placental aromatization of maternal and fetal androgens, driven by fetal adrenal DHEA-S

Q7. Which clinical use of oestriol preparation is well-established in gynecological practice?

  • Oral systemic hormone replacement for osteoporosis prevention
  • Topical or vaginal oestriol for symptomatic vulvovaginal atrophy in menopause
  • First-line contraceptive when used alone
  • Emergency contraception within 72 hours

Correct Answer: Topical or vaginal oestriol for symptomatic vulvovaginal atrophy in menopause

Q8. Which feature explains why maternal oestriol is a better marker of fetal well-being than maternal estradiol?

  • Oestriol is exclusively maternal in origin and unaffected by fetus
  • Oestriol production depends on intact fetal adrenal and hepatic function plus placental conversion
  • Estradiol cannot cross the placenta at all
  • Oestriol has a longer half-life making it more stable

Correct Answer: Oestriol production depends on intact fetal adrenal and hepatic function plus placental conversion

Q9. Which enzyme deficiency in the fetus would most directly reduce maternal oestriol levels?

  • Placental aromatase deficiency
  • Fetal 21-hydroxylase deficiency
  • Fetal alcohol dehydrogenase deficiency
  • Maternal 5-alpha reductase deficiency

Correct Answer: Placental aromatase deficiency

Q10. In pharmacokinetic terms, why does oral oestriol have variable systemic effects compared with parenteral routes?

  • Short intestinal transit time prevents absorption
  • Extensive first-pass hepatic metabolism and conjugation reduce bioavailability
  • It non-specifically binds to dietary proteins in the gut
  • Oestriol is unstable at gastric pH and degrades before absorption

Correct Answer: Extensive first-pass hepatic metabolism and conjugation reduce bioavailability

Q11. Which statement about oestriol receptor interaction is correct?

  • Oestriol binds estrogen receptor beta with higher affinity than estradiol
  • Oestriol has preferential antagonistic action at estrogen receptors
  • Oestriol is a weak agonist at both ERα and ERβ with partial agonist effects in some tissues
  • Oestriol exclusively activates membrane estrogen receptors but not nuclear receptors

Correct Answer: Oestriol is a weak agonist at both ERα and ERβ with partial agonist effects in some tissues

Q12. Which drug interaction is most likely to lower plasma oestriol levels when administered concurrently?

  • Ketoconazole (CYP inhibitor)
  • Rifampin (hepatic enzyme inducer)
  • Probenecid (uric acid transporter inhibitor)
  • Spironolactone (aldosterone antagonist)

Correct Answer: Rifampin (hepatic enzyme inducer)

Q13. What is the main analytical difference between measuring unconjugated oestriol in serum versus urinary estriol metabolites?

  • Serum uE3 requires enzymatic hydrolysis while urine does not
  • Urinary measures represent conjugated metabolites and reflect total production and clearance
  • Serum assays always overestimate levels due to cross-reactivity
  • Urine assays quantify only free, unmetabolized oestriol

Correct Answer: Urinary measures represent conjugated metabolites and reflect total production and clearance

Q14. Which prenatal screening panel commonly includes unconjugated oestriol?

  • First-trimester combined test (PAPP-A and nuchal translucency only)
  • Quadruple screen (AFP, hCG, uE3, inhibin A)
  • Cell-free fetal DNA test
  • Maternal serum thyroid function panel

Correct Answer: Quadruple screen (AFP, hCG, uE3, inhibin A)

Q15. From a pharmaceutical formulation perspective, why are vaginal oestriol preparations advantageous for local therapy?

  • They maximize systemic absorption for menopausal symptom control
  • They deliver high local concentration with minimal systemic exposure due to local mucosal uptake
  • They are cheaper to manufacture than oral tablets
  • They bypass stability issues associated with estradiol

Correct Answer: They deliver high local concentration with minimal systemic exposure due to local mucosal uptake

Q16. Which adverse effect is classically associated with systemic estrogen therapy and relevant to oestriol when systemically absorbed?

  • Hypoglycemia
  • Thromboembolic events
  • Excessive hair loss
  • Hyperkalemia

Correct Answer: Thromboembolic events

Q17. How does the placental transfer of steroid precursors contribute to oestriol biosynthesis?

  • Placenta transfers cholesterol to fetus where it is converted to oestriol
  • Fetal adrenal produces DHEA-S which is converted by fetal liver to 16α-hydroxy-DHEA-S and aromatized in placenta to oestriol
  • Maternal cortisol is converted in placenta to oestriol directly
  • Placenta directly synthesizes oestriol from maternal testosterone only

Correct Answer: Fetal adrenal produces DHEA-S which is converted by fetal liver to 16α-hydroxy-DHEA-S and aromatized in placenta to oestriol

Q18. In drug stability terms, what is a key consideration when compounding oestriol topical creams?

  • Oestriol is highly photosensitive and requires opaque packaging and antioxidant-containing base
  • Oestriol is stable in all bases at room temperature indefinitely
  • Oestriol reacts with water to form inactive polymers, so anhydrous bases are mandatory
  • There are no concerns; mixing with any steroid is safe

Correct Answer: Oestriol is highly photosensitive and requires opaque packaging and antioxidant-containing base

Q19. Which laboratory finding would you expect in a normal third-trimester pregnancy regarding oestriol?

  • Marked decline of maternal unconjugated oestriol compared with first trimester
  • Progressive rise in maternal unconjugated and conjugated oestriol, peaking near term
  • No change throughout pregnancy from baseline nonpregnant levels
  • Intermittent spikes unrelated to gestational age

Correct Answer: Progressive rise in maternal unconjugated and conjugated oestriol, peaking near term

Q20. Which statement describes the role of enterohepatic circulation in oestriol pharmacokinetics?

  • Oestriol is not subject to enterohepatic recycling and is excreted unchanged
  • Conjugated oestriol excreted into bile can be deconjugated by gut flora and reabsorbed, prolonging exposure
  • Enterohepatic circulation eliminates oestriol exclusively via feces
  • Gut bacteria synthesize oestriol de novo, increasing levels

Correct Answer: Conjugated oestriol excreted into bile can be deconjugated by gut flora and reabsorbed, prolonging exposure

Q21. Which structural feature distinguishes oestriol from estradiol chemically?

  • Oestriol has an extra hydroxyl group at C16 compared with estradiol
  • Oestriol lacks the aromatic A-ring typical of estrogens
  • Oestriol contains a sulfate group in its core structure
  • Oestriol is a C19 steroid while estradiol is C18

Correct Answer: Oestriol has an extra hydroxyl group at C16 compared with estradiol

Q22. For a B. Pharm student designing an assay, which pre-analytical factor most affects measured maternal uE3?

  • Time of day of sample collection only
  • Maternal hydration and urine concentration (creatinine correction for spot urine)
  • Fetal sex exclusively
  • Mother’s hemoglobin concentration

Correct Answer: Maternal hydration and urine concentration (creatinine correction for spot urine)

Q23. In the context of fetal monitoring, an isolated low uE3 but normal hCG and AFP most likely warrants which next step?

  • No further evaluation; report as normal variant
  • Repeat testing, detailed ultrasound and consider fetal genetic evaluation if persistent
  • Immediate termination of pregnancy
  • Start empiric maternal estrogen therapy

Correct Answer: Repeat testing, detailed ultrasound and consider fetal genetic evaluation if persistent

Q24. Which pharmacological rationale supports using low-dose vaginal oestriol instead of systemic estradiol for local atrophy?

  • Vaginal oestriol is systemically more potent than estradiol
  • Vaginal application provides localized trophic effect with minimal systemic estrogenic load, reducing systemic risks
  • Estradiol is ineffective on vaginal epithelium
  • Vaginal oestriol irreversibly binds to local estrogen receptors preventing recurrence

Correct Answer: Vaginal application provides localized trophic effect with minimal systemic estrogenic load, reducing systemic risks

Q25. Which pharmacodynamic effect of oestriol is most relevant to its therapeutic use in vaginal atrophy?

  • Induction of systemic coagulation factors
  • Stimulation of local epithelial proliferation and increased glycogen production
  • Direct antimicrobial activity against vaginal pathogens
  • Inhibition of local estrogen receptor expression

Correct Answer: Stimulation of local epithelial proliferation and increased glycogen production

Q26. When interpreting laboratory uE3 results, which maternal condition can falsely lower measured values?

  • Maternal smoking leading to enzyme induction
  • Maternal ingestion of cholic acid supplements
  • Maternal use of glucocorticoids that alter fetal adrenal function
  • Maternal vegetarian diet

Correct Answer: Maternal use of glucocorticoids that alter fetal adrenal function

Q27. Which statement about oestriol’s half-life and dosing frequency is accurate for topical vaginal use?

  • Due to rapid systemic clearance, topical vaginal oestriol typically requires frequent initial dosing but maintenance may be intermittent
  • It has an extremely long half-life so single-dose therapy is curative
  • Topical oestriol accumulates causing daily dosing to be unsafe
  • Once-weekly dosing is standard for all patients

Correct Answer: Due to rapid systemic clearance, topical vaginal oestriol typically requires frequent initial dosing but maintenance may be intermittent

Q28. Which regulatory/pharmaceutical consideration applies when compounding oestriol creams in community pharmacies?

  • No need for stability testing if compounded for immediate use
  • Compounded preparations should follow validated protocols, use appropriate vehicle, label for storage, and consider potency/stability data
  • Oestriol compounding is exempt from sterility and documentation requirements
  • Oestriol should only be compounded with estradiol to increase potency

Correct Answer: Compounded preparations should follow validated protocols, use appropriate vehicle, label for storage, and consider potency/stability data

Q29. In the mechanism of action, which genomic effect is associated with oestriol binding to nuclear estrogen receptors?

  • Immediate non-genomic ion channel opening only
  • Receptor dimerization, DNA estrogen response element binding, and modulation of gene transcription—although weaker than estradiol
  • Direct covalent modification of DNA bases
  • Selective degradation of estrogen receptor without transcriptional effects

Correct Answer: Receptor dimerization, DNA estrogen response element binding, and modulation of gene transcription—although weaker than estradiol

Q30. For a B. Pharm student evaluating drug safety, which patient history would most strongly contraindicate systemic oestrogen therapy including formulations that elevate oestriol?

  • History of migraine without aura
  • History of estrogen receptor-positive breast cancer or active thromboembolic disease
  • Mild hyperlipidemia on diet control
  • Controlled hypertension on monotherapy

Correct Answer: History of estrogen receptor-positive breast cancer or active thromboembolic disease

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